Many known chemical products such as surfactants, plasticizers, solvents, and polymers are currently manufactured from non-renewable, expensive, petroleum-derived or natural gas-derived feedstock compounds. High raw material costs and uncertainty of future supplies requires the discovery and development of surfactants, plasticizers, solvents, and polymers that can be made from inexpensive renewable biomass-derived feedstocks and by simple chemical methods. Using renewable resources as feedstocks for chemical processes will reduce the demand on non-renewable fossil fuels currently used in the chemical industry and reduce the overall production of carbon dioxide, the most notable greenhouse gas.
A potential source of materials that are useful as chemical building blocks are cyclic ketals and acetals of oxocarboxylates with polyols. It is known, for example, that polyhydric alcohols, or polyols, having 1,2 and 1,3 hydroxy conformations can react with a ketone or aldehyde to form a cyclic ketal or an acetal (Carey, F. A. and Sundberg, R. J., “Advanced Organic Chemistry Part B: Reactions and Synthesis” 2nd ed., © 1983, Plenum Press, NY, N.Y., p. 544). The 1,2 and 1,3 configurations of hydroxyl groups on a hydrocarbon chain are shown below as (a) and (b), respectively.
Diols such as 1,2-ethane diol (ethylene glycol) and 1,3 propanediol (propylene glycol) are examples of such polyols. Diols having a 1,2 hydroxyl group configuration will form dioxolanes when reacted with ketone or aldehyde moieties, while 1,3 diols will form dioxanes.
Ketal acids and esters are starting materials from which the compounds of the invention are synthesized. Ketals of glycerol and levulinic acid or an ester thereof are described in U.S. Patent Publication No. 2008/0242721, the entirety of which is incorporated herein by reference. The ketal reaction product of glycerol with a levulinate results in a monoketal acid or monoketal ester as shown below,
wherein R is hydrogen or an alkyl group. Combining a levulinate ester with glycerol provides a levulinate-glycerol ketal that is bifunctional and available from 100% renewable feedstocks. The levulinate-glycerol ketals are useful for synthesis of a wide variety of surfactants, plasticizers, polymers, and the like. Other monoketals synthesized from various oxocarboxylic acids or esters thereof such as acetoacetates and pyruvates, with triols such as 1,1,1-trimethylolpropane and 1,1,1-trimethylolethane, are described in International Patent Application No. PCT/US2008/075225. The monoketal acids and esters have the general structure
wherein a is 0 or 1, b is 0 or 1, R3 is hydrogen or an alkyl group having between 1 and 12 carbons, R4 is an alkyl group having between 1 and 12 carbons, and X is any substituent. Substituents R3 and R4 may further be substituted with one or more functional groups, such as halogen, ether, cyano, and the like. These materials are useful as, or for the synthesis of, a wide variety of surfactants, plasticizers, polymers, and the like. The compounds described in these applications are capable of self condensation to provide oligomers or polymers having hydroxyl endgroups, and further are capable of condensation with one or more diols to give oligomeric or polymeric polyols. Monoketals are starting materials for the synthesis of the compounds of the invention.
Polyketal acids and polyketal esters, which are compounds having at least two contiguous or semi-contiguous ketal acid or ketal ester moieties per molecule, are described in International Patent Application No. PCT/US2008/079337. Various oxocarboxylic acids and esters are useful in synthesizing the disclosed compounds, as well as various tetrols and higher polyols. In one nonlimiting example, combining a levulinate ester with erythritol provides a bisketal starting material from renewable feedstocks. This reaction is shown below,
wherein R is hydrogen or an alkyl group. Further, the polyketal acids and esters are useful as, or for the synthesis of, a wide variety of surfactants, plasticizers, polymers, and the like, as disclosed in the application.
Efficient synthetic routes to form various compounds based on the ketals or acetals of oxocarboxylates are described in International Patent Application No. PCT/US08/79083. The synthetic routes described therein are useful as a basis for efficient reaction of a number of oxocarboxylic acids and esters thereof with diols, triols, and higher polyols and are useful in making any of the above mentioned ketal moieties, all of which are starting materials for the compounds of the invention.